Adjustable offset bushing

Abstract

An orthopaedic instrumentation having an intermediate piece that has an opening for receiving an intramedullary reference. The intermediate piece such as a tibial template or a cutting guide is located on the resected tibia or femur in a manner that it optimally covers the resected surface of the tibia or the femur. A bushing guide is provided for mounting on the intermediate piece. The bushing guide has a circular opening. An offset bushing is rotatably mounted in the opening in the bushing guide. A trigger flange is slidably mounted on the offset bushing. The trigger flange can slide back and forth relative to the offset bushing. An indicia is formed on the upper surface of trigger flange. The indicia when aligned with one of the indicia on the offset bushing body measures the offset of center of a bore in the trigger flange from center of the offset bushing. The offset bushing can rotate around its longitudinal axis in the opening in the bushing guide. Indicia on the offset bushing may be used to measure the orientation of the center of the hole in the trigger with respect to the center of bushing body.

The invention claimed is: 
     
       1. A joint prosthesis instrument comprising:
 an intramedullary reference; 
 a plate adapted to attach to a bone; 
 a rotatable bushing having a top surface, a bottom surface, and an oblong hole extending between the top surface and the bottom surface, wherein the oblong hole has an elongated opening with elongated sides extending along the top surface, and wherein the rotatable bushing is adapted to rotate with respect to the plate; and 
 a trigger flange slidably mounted in the bushing, the trigger flange having a first hole positioned along a length of the elongated opening of the oblong hole, the first hole being sized to allow the intramedullary reference to slide in the hole, wherein by rotating the bushing and sliding the trigger flange the first hole in the trigger flange can be located in a position that can receive the intramedullary reference, thereby measuring the angular orientation and linear distance of the intramedullary reference with respect to a fixed point on the plate. 
 
     
     
       2. The joint prosthesis instrument of  claim 1 , further comprising:
 a bushing guide, the bushing guide having a first opening to rotatably engage the rotatable bushing in the first opening. 
 
     
     
       3. The joint prosthesis instrument of  claim 2 , further comprising:
 a second opening formed in the plate, at least a portion of the second opening being aligned with the first opening in the bushing guide. 
 
     
     
       4. The joint prosthesis instrument of  claim 3 , wherein at least a portion of the oblong hole is aligned with the first opening in the plate. 
     
     
       5. The joint prosthesis instrument of  claim 4 , further comprising:
 first indentations formed on the bushing, the first indentations being spaced a fixed distance apart from each other. 
 
     
     
       6. The joint prosthesis instrument of  claim 5 , further comprising:
 a handle attached to the bushing guide; and 
 a first spring loaded pin attached to the handle, wherein the first spring loaded pin engages the indentations on the bushing to lock the bushing in place. 
 
     
     
       7. The joint prosthesis instrument of  claim 2 , further comprising:
 a top surface having markings used to determine linear distance by which the intramedullary reference is offset from the fixed point on the plate. 
 
     
     
       8. The joint prosthesis instrument of  claim 7 , further comprising:
 at least one raised portion formed on the bushing, the raised portion having a side surface, a second indentations formed on the side surface of the raised position; 
 a second spring loaded pin mounted on the trigger flange, the second spring loaded pin engaging the second indentations to lock the trigger flange in place. 
 
     
     
       9. A joint prosthesis instrument comprising:
 an intramedullary reference; 
 an intermediary piece adapted to attach to a bone; 
 a rotatable bushing adapted to rotate with respect to the intermediary piece, the rotatable bushing having an outer surface; and 
 a trigger flange slidably mounted in the bushing, the trigger flange having a first hole, the first hole being sized to allow the intramedullary reference to slide in the hole, wherein by rotating the bushing and sliding the trigger flange in a longitudinal direction across at least a portion of the outer surface of the rotatable bushing, the intramedullary reference can be being positioned within the first hole in the trigger flange, thereby measuring the angular orientation and linear distance of the intramedullary reference with respect to a fixed point on the intermediate piece. 
 
     
     
       10. The joint prosthesis instrument of  claim 9 , wherein the intermediary piece is selected from a group consisting of a tibial plate and a cutting guide. 
     
     
       11. The joint prosthesis instrument of  claim 10 , further comprising:
 a bushing guide, the bushing guide having a first opening to rotatably engage the rotatable bushing in the first opening. 
 
     
     
       12. The joint prosthesis instrument of  claim 11 , further comprising:
 a second opening formed in the intermediate piece, at least a portion of the second opening being aligned with the first opening in the bushing guide. 
 
     
     
       13. The joint prosthesis instrument of  claim 12 , wherein the rotatable bushing has an oblong hole, and at least a portion of the oblong hole is aligned with the first opening in the intermediate piece. 
     
     
       14. The joint prosthesis instrument of  claim 13 , further comprising:
 first indentations formed on the rotatable bushing, the first indentations being spaced a fixed distance apart from each other. 
 
     
     
       15. The joint prosthesis instrument of  claim 14 , further comprising:
 a pin insertable in the bushing guide, wherein the pin engages the indentations on the bushing to lock the bushing in place. 
 
     
     
       16. The joint prosthesis instrument of  claim 11 , further comprising:
 markings used to determine linear distance by which the intramedullary reference is offset from the fixed point on the intermediate piece. 
 
     
     
       17. The joint prosthesis instrument of  claim 16 , further comprising:
 second indentations formed on the side surface of the rotatable bushing that faces the side surface of the trigger flange; 
 a spring loaded pin mounted on the trigger flange, the spring loaded pin engaging the second indentations to lock the trigger flange in place. 
 
     
     
       18. The joint prosthesis instrument of  claim 9 , wherein the rotatable bushing further comprises a bushing body having a recess, wherein the trigger flange is positioned within said recess of the bushing body and is capable of sliding within the recess. 
     
     
       19. The joint prosthesis instrument of  claim 1 , further comprising an axis extending through the oblong hole and wherein the first hole is aligned with the axis. 
     
     
       20. The joint prosthesis instrument of  claim 1 , wherein when the bushing is rotated and the trigger is slid, the first hole in the trigger flange is aligned with the intramedullary reference. 
     
     
       21. The joint prosthesis instrument of  claim 9 , wherein the trigger flange has a top surface and a bottoms surface, and wherein when the trigger flange is slid in the longitudinal direction across at least a portion of the outer surface of the rotatable bushing, the bottom surface of the trigger flange moves across at least a portion of the outer surface. 
     
     
       22. The joint prosthesis instrument of  claim 9 , wherein the rotatable bushing further includes an interior hole and wherein when the trigger flange is slid in a longitudinal direction across at least a portion of the outer surface of the rotatable bushing, the first hole in the trigger flange can be axially aligned with at least a portion of the interior hole.